Polyurethanes are a class of polymers used extensively in the preparation of a large variety of products. Polyurethanes have a wide range of physical properties. The properties of a particular polyurethane will depend upon the exact chemical composition of the polyurethane polymer. Some polyurethanes are soft and spongy, while others are rigid.
Many situations call for an object with structural integrity, a waterproof covering, and/or detailed features on the surface of the object. For example, for the comfort of the passengers, seats on marine vehicles need a cushion portion wherein the cushion portion often needs a waterproof covering, some inner structure, detailed features such as emblems, and some means for attaching the cushion to the seat frame. These cushions are often assembled by covering a piece of cushiony material, for example foam, with a piece of vinyl or leather. If an emblem is desired, it is often stitched onto the covering, creating holes in the covering. In addition, the vinyl is often stapled, screwed, or glued to the structure of the seat which is often, for example, made of wood. The exposure of the seat and seat cushion to the moisture encountered in a marine environment can cause, for example, the staples and wood to degrade with time and/or the foam to mildew. This degradation can be due to the moisture penetrating the holes through which the staples punctured the vinyl covering to secure the vinyl covering to the wood.
In many instances, it is advantageous to prepare articles which have a polyurethane layer encapsulating an inner structure, for example, polyurethane foam. Although such polyurethane covered objects are useful for many applications, a frequent problem with such products involves the separation of the seams produced during the manufacturing process. Such separation is particularly common when the product is subjected to high temperatures, changes in temperature, or if the product is exposed to salt water or other harsh conditions. Because polyurethane articles are often used in the automotive and boating industries, separation of seams presents an important limitation to the usefulness of these products.
Currently, the marine and transportation industry typically employ in-house upholstery or outside vendors to make internal parts that act as cushioning or covering for their interiors. This is a very time-consuming and costly process that entails wrapping either a vinyl or leather sheet foam over a wood or plastic base. The material is either glued, stapled, or sewn onto the backing. With time, the wood either dry rots or the vinyl tears and opens the interior to water absorption. This causes the part to require either repair or replacement.
There exists a clear need for a process which can reliably and inexpensively produce a polyurethane object with a waterproof covering, some inner structure, detailed features on the covering, and/or some means for attaching the object to external structures. A procedure which could cost-effectively produce such polyurethane objects is particularly needed.